A transition metal complex containing a phosphine compound as a ligand, especially a chiral phosphine compound, plays an extremely important role supporting stereo-selective production of organic compounds in various fields such as such as perfumes, pharmaceuticals, agricultural chemicals, and liquid crystals.
On the other hand, as to these catalysts, since transition metals to be used are expensive, reduction of used amount, or development of methods for recovering thereof had been demanded, and many methods already have been reported.
A method wherein a phosphine ligand is converted to a water-soluble derivative, a reaction is carried out in an aqueous solution using a transition metal complex thereof, a product is taken out by separation, and thereafter, the residual aqueous phase is reused for a next reaction, is one of means solving for this problem. As a method for making a water-soluble phosphine ligand, various methods are attempted, and when aryl phosphines are taken as an example, sulfonation of an aromatic ring such as a phenyl group and a naphthalene ring in a molecule, is most often used.
For example, in Non-Patent Document 1, three phenyl groups of triphenylphosphine are substituted with two or three sulfonic acid groups and substituted with eight sulfonic acid groups, are reported.
Further, in Patent Document 1, BINAP wherein 5 and 5′ positions of a bi-naphthyl group are sulfonated, and in Non-Patent Document 2, BINAP wherein all of four phenyl groups are sulfonated, are respectively described.
In Non-Patent Document 3, four ligands of (S, S)-cyclobutanediop, (S, S)-Chiraphos, (S, S)—BDPP, and (R)-Prophos which are tetra-sulfonated, are reported. In Non-Patent Document 4, a sulfonated diphosphine ligand NAPHOS are reported.
Non-Patent Document 1: Angew. Chem. Int. Ed. Engl., 1995, 34, No. 7, pp. 811-3,
Non-Patent Document 2: Tetrahedron Asymmetry, Vol. 4, No. 12, pp. 2461-8(1993),
Non-Patent Document 3: Organometallics, 1989, No. 8, pp. 542-7,
Non-Patent Document 4: Journal of Organometallic Chem. 532 (1997) pp. 243-9, and
Patent Document 1: JP-A-5-170-780.